Actuator

ABSTRACT

This invention relates to an actuator which consists of a hydraulic or pneumatic drive, which in accordance with the invention is combined with an electromechanical drive in one constructional unit, the hydraulic or pneumatic drive being the normal drive of the actuator and the electromechanical drive being used for an alternative actuation of the actuator.

This invention relates to an actuator which consists of a hydraulic or pneumatic drive. Actuators employed in aircraft systems must satisfy particular safety standards. In conventional systems, in which the actuators are actuated by hydraulic or pneumatic drives, parallel second hydraulic or pneumatic systems for actuating the actuators are provided for an alternative actuation in the case of a failure of the first system, in order to maintain the operability of the aircraft system. Providing a second hydraulic or pneumatic system for each actuator is costly and expensive. In addition, these drives are also heavy, which is disadvantageous in particular when using the same as component of an aircraft system. When two parallel hydraulic or pneumatic systems are used, there can also occur a total functional loss of the actuator unit, for instance when the piston gasket in the actuator is defective.

Therefore, it is the object of the present invention to provide an actuator with improved functional safety, which is more compact and thus of a lighter design.

In accordance with the invention, this object is solved by the features of claim 1. In an actuator which consists of a hydraulic or pneumatic drive, an electromechanical drive is combined in one constructional unit as alternative drive, the hydraulic or pneumatic drive being the normal drive of the actuator, and the electromechanical drive being used for an alternative actuation of the actuator. This alternative actuation only comes into effect, when the hydraulic or pneumatic first drive fails. By combining the hydraulic or pneumatic drive with the electromechanical drive on the one hand and by integrating the same in one constructional unit, i.e. in one device, on the other hand, a particularly compact and lightweight actuator unit is created, which is suited in particular for use in flight control systems. Advantageous aspects of the invention can be taken from the sub-claims.

Accordingly, the electromechanical drive can be arranged in series with the hydraulic or pneumatic drive. Alternatively, the electromechanical drive can be arranged parallel to the hydraulic or pneumatic drive.

The electromechanical drive can loosely be connected with the hydraulic or pneumatic drive, performing no movement in normal operation and being actuatable only for the alternative movement. On the other hand, the electromechanical drive can firmly be connected with the hydraulic or pneumatic drive, performing the movement of the hydraulic or pneumatic drive without load, i.e. passively, in normal operation and being actuatable as active drive only for the alternative movement.

Further features, details and advantages can be taken from the embodiments which are illustrated schematically in the drawing, in which:

FIG. 1 shows a first, purely schematically illustrated embodiment of the actuator in accordance with the invention, and

FIG. 2 shows a second embodiment of the actuator in accordance with the invention in a schematic representation.

In FIG. 1, an actuator 10 is shown purely schematically. Said actuator 10 includes any component 12 movable in and against the direction of arrow, which is normally movable via a hydraulic or pneumatic drive 14 which here likewise is shown only schematically.

In the embodiment as shown in FIG. 1, an electromechanical drive 16 is disposed in series with said hydraulic or pneumatic drive 14, which centrally includes a spindle or toothed rack 18 which can be actuated via an electric motor 20 and a transmission 22 coupled thereto.

FIG. 1 does not show in detail how the electromechanical drive 16 is connected with the hydraulic or pneumatic drive 14 and how these two drives are connected with the actuating means 12. This can be effected in a manner known to those skilled in the art. The electromechanical drive can loosely be connected with the hydraulic or pneumatic drive, performing no movement in normal operation and being actuatable only for the alternative movement. Alternatively, the electromechanical drive 16 can also firmly be connected with the hydraulic or pneumatic drive 14, the electromechanical drive 16 performing the movement of the hydraulic or pneumatic drive in normal operation and being actuatable as active drive only for the alternative movement.

FIG. 2 shows an alternative embodiment, which basically corresponds to the one shown in FIG. 1. In this case, however, the electromechanical drive 16 is not arranged in series with, but parallel to the hydraulic or pneumatic drive 14. The remaining functions can be realized similar to the embodiment as shown in FIG. 1.

What is essential in the embodiments as shown in FIGS. 1 and 2 is the fact that the hydraulic and pneumatic drive units are realized in combination with the electromechanical drive unit in one constructional unit, i.e. in one device. As a result, a second hydraulic or pneumatic system can be omitted, the absolute separation of two systems still being ensured. The actuator in accordance with the invention is of light weight, as fewer tubes, less oil volume and the like must be provided here. Safety also is increased, as for instance in the case of a defective piston gasket in the actuator, the actuator still can be actuated due to the presence of the electromechanical drive unit 16. 

1. An actuator, comprising a hydraulic or pneumatic drive, characterized in that it is combined with an electromechanical drive in one constructional unit, the hydraulic or pneumatic drive being the normal drive of the actuator and the electromechanical drive being used for an alternative actuation of the actuator.
 2. The actuator as claimed in claim 1, characterized in that the electromechanical drive is arranged in series with the hydraulic or pneumatic drive.
 3. The actuator as claimed in claim 1, characterized in that the electromechanical drive is arranged parallel to the hydraulic or pneumatic drive.
 4. The actuator as claimed in claim 1, characterized in that the electromechanical drive is loosely connected with the hydraulic or pneumatic drive, performing no movement in normal operation and being actuatable only for the alternative movement.
 5. The actuator as claimed in claim 1, characterized in that the electromechanical drive is firmly connected with the hydraulic or pneumatic drive, performing the movement of the hydraulic or pneumatic drive without load in normal operation and being actuatable as active drive only for the alternative movement.
 6. The actuator as claimed in claim 2, characterized in that the electromechanical drive is loosely connected with the hydraulic or pneumatic drive, performing no movement in normal operation and being actuatable only for the alternative movement.
 7. The actuator as claimed in claim 3, characterized in that the electromechanical drive is loosely connected with the hydraulic or pneumatic drive, performing no movement in normal operation and being actuatable only for the alternative movement.
 8. The actuator as claimed in claim 2, characterized in that the electromechanical drive is firmly connected with the hydraulic or pneumatic drive, performing the movement of the hydraulic or pneumatic drive without load in normal operation and being actuatable as active drive only for the alternative movement.
 9. The actuator as claimed in claim 3, characterized in that the electromechanical drive is firmly connected with the hydraulic or pneumatic drive, performing the movement of the hydraulic or pneumatic drive without load in normal operation and being actuatable as active drive only for the alternative movement. 